Abstract
ObjectivesSwab-based nasal screening is commonly used to identify asymptomatic carriage of Staphylococcus aureus in patients. Bacterial detection depends on the uptake and release capacities of the swabs and on the swabbing technique itself. This study investigates the performance of different swab-types in nasal MRSA-screening by utilizing a unique artificial nose model to provide realistic and standardized screening conditions.MethodsAn anatomically correct artificial nose model was inoculated with a numerically defined mixture of MRSA and Staphylococcus epidermidis bacteria at quantities of 4×102 and 8×102 colony forming units (CFU), respectively. Five swab-types were tested following a strict protocol. Bacterial recovery was measured for direct plating and after elution into Amies medium by standard viable count techniques.ResultsMean recovered bacteria quantities varied between 209 and 0 CFU for MRSA, and 365 and 0 CFU for S. epidermidis, resulting swab-type-dependent MRSA-screening-sensitivities ranged between 0 and 100%. Swabs with nylon flocked tips or cellular foam tips performed significantly better compared to conventional rayon swabs referring to the recovered bacterial yield (p<0.001). Best results were obtained by using a flocked swab in combination with Amies preservation medium. Within the range of the utilized bacterial concentrations, recovery ratios for the particular swab-types were independent of the bacterial species.ConclusionsThis study combines a realistic model of a human nose with standardized laboratory conditions to analyze swab-performance in MRSA-screening situations. Therefore, influences by inter-individual anatomical differences as well as diverse colonization densities in patients could be excluded. Recovery rates vary significantly between different swab-types. The choice of the swab has a great impact on the laboratory result. In fact, the swab-type contributes significantly to true positive or false negative detection of nasal MRSA carriage. These findings should be considered when screening a patient.
Highlights
Nasal carriage of S. aureus is present in 20–30% of the population [1,2] and is a major risk factor for various purulent endogenous infections as well as bacterial transmission both in community and nosocomial environments [2,3,4]
With respect to bacterial recovery rates in nasal MRSAscreening, the present study revealed significantly better performance of flocked and cellular foam tipped swabs compared to conventional rayon tipped swabs
Close to real-life conditions approach for swab testing, this study outlines the huge impact of the swab-type on the laboratory results
Summary
Nasal carriage of S. aureus is present in 20–30% of the population [1,2] and is a major risk factor for various purulent endogenous infections as well as bacterial transmission both in community and nosocomial environments [2,3,4]. As S. aureus predominantly colonizes the anterior part of the nasal cavity [12] swab based screening techniques are commonly used to identify such carriers. Utilizing the correct swabbing technique can significantly improve the bacterial recovery rate in nasal screening even within the same swab-type [21]. Commonly used swabs with different tips, like rayon, cellular foam, or nylon flocked tips, vary significantly with respect to uptake and release of liquid and bacteria, depending on the clinical setting, i.e. if used on dry surfaces such as skin and other epithelia or on wet surfaces such as operation wounds [22]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
